This invention relates to a folding joint, and particularly to a lockable folding joint for a foldaway ladder.
FIG. 1 shows a conventional folding joint which has two flat hollow arms 101, 102, one of which has a substantially flat head 1011, and the other of which has a forked head 1021. The head 1011 is sandwiched by and pivoted to the forked head forming an angle therebetween. These arms can be locked against one another at any desired angle by means of a detent block 105 which can selectively engage one of the notches 1012 provided in the periphery of the head 101. A mechanism for holding and urging the detent block includes a substantially V-shaped plate member 103 which is mounted in the hollow arm 102 by engaging the hook ends thereof with the edges of apertures 1022 in the arm 102. A spring loaded rod 104 attached to the V-shaped member urges and holds the detent member. A spring plate 107 is attached to a pin 108 with its rolled end and extends to the detent block 105 to hold the detent block against the spring loaded rod 104, thereby holding the detent block resiliently and firmly. A pin 109 is provided to depress the spring plate 107 so as to prevent the hook end of the spring plate 107 from moving away from the detent block 105. This mechanism is complicated and difficult to assemble.